Finding solution to leaking valve cover gaskets...

[lochenjons]

1970 charger with a 383. I’ve taken the valve covers on and off and changed gaskets about 6 times now and I’m looking for this next time to be the last.

both valve covers were leaking from the rear of the block by the firewall so I pulled them off and replaced them with the cork gasket. That didn’t work so I tried a better gasket (fel pro rubber/cork). Same issue. Tried the moroso perm align gaskets. Nope! Put RTV on both sides of the gasket. Same issue! Took valve covers off and switched the sides with a new gasket with RTV. No luck. The leak only kind of slowed down. And I’ve always cleaned the head surface with acetone and made sure it was nice and clean before continuing.

I redid my valley pan gasket thinking that maybe that was the issue. It wasn’t but now I have a new valley pan gasket that doesn’t leak. I’ve inspected the valve covers and they’re straight. They’re the aluminum mopar performance ones. And I’ve properly torqued them down. They’re not too tight at all. A little bit past snug.
Any suggestions here? I’ve always heard you shouldn’t have to put RTV on the valve cover gaskets and I never have done it in the past. Just wondering where to go from here. Any help would be appreciated.

 

[GetX'd]

Had the same problem with my Mopar Performance covers. It turned out they were not level in that same corner. Had to level them out to finally get a good seal.

 

[Bill Monk]

I struggled with the same issue and finally cured it with cometic gaskets. They are expensive and they are sold one per package so you have to buy two to get the set. I can't say if they're that good or it was simple dumb luck but I don't have a leak now

 

[Outsider]

After getting shut down by the starter on the line for a drip couple times back in the '80s I made a fix that worked. I had a certain set of heads that I had tried numerous gaskets and covers on with no luck. Set up the heads on the Bridgeport and ran in the rail and it had low spots over 1/8" from casting irregularities. Milled the rail and could use any cover or gasket without problems.

 

[khryslerkid]

I have a set of Cal Customs aluminum covers and they're not perfectly flat. This is what I used and they don't leak. I used the thick Felpro Rubber/Cork gaskets.

Start off with perfectly clean and dry valve covers. No silicone residue, no oil containment (clean bare metal with lacquer thinner or parts cleaner. Flatten out the area at each hole so it's flat, not dented from the last time they were tightened. Perfectly clean the head also in the same manner.

Use the black felpro gasket and glue it to the valve cover with 3M black weather strip adhesive. Let it dry.

Then apply an even coat of Permatex Ultra Black Gasket Maker to the gasket. 1/8" Thick.

Set the cover on the head immediately and only finger tighten the hardware till the gasket maker just starts to ooze out. Let it dry for one hour and then hand tighten with a 1/4 drive socket. You don't need to tighten them any more than if you were useing screws for fasteners and a screwdriver to tighten them.

Let the sealer cure for 24 hours before running the engine. Guarantee this will work if you follow the directions to the letter.

I even pulled these once for inspection and place them back on and they're still dry.

 

[R/T Boy 67]

Put a thin layer of grease on the covers or head and install without gaskets. You should be able to see a non contact point if there is one.

 

[jz61]

stock heads im assuming? the surface of the heads where to gasket sits is a small rounded area, not the best for sealing. mopar should have milled this flat, but that would be too easy! what i did with mine and they havnt leaked since,4yrs or so. when the valve cover is off clean both sides. and i paid attention to rear of head near headers or manifold, i soaked up all oil that collects in this area. i used the old indian head gasket cement, first on the valve cover, let it get tacky, put gasket onto cover then put indian head onto head where the gasket meets. i also used hold downs or spreaders, i got from classic and new bolts all around. snug it down and let sit for 24hrs, maybe i got lucky, but hasnt leaked since! now only if i can stop my tranny pan gasket from leaking id be happy!

 

[70chall440]

One of the biggest mistakes made with RTV and gasket maker is assembling too quickly and tightly; you usually only manage to push out the sealer. The advice above is good, don't tighten it down right away, have to let the RTV solidify some.

 

[Dennis H]

FelPro. Gentle snug after heat cycles. Pre glued black stuff and parked in sun a bit.

 

[Bad B-rad]

I have always had great luck with Indian head cement, Permatex sells it, but calls it aviation cement.
Try and get the covers and matting surface as true as you can, and give the aviation cement a try with some cork gaskets.

 

[dart4forte]

One of the biggest mistakes made with RTV and gasket maker is assembling too quickly and tightly; you usually only manage to push out the sealer. The advice above is good, don't tighten it down right away, have to let the RTV solidify some.

When I glue my VC gaskets with RTV I use it sparingly. Once I put the gasket on I lay them flat on the floor overnight. No issues.

 

[lochenjons]

Wow lots of replies ! Thank you everyone for your advice, I truly truly appreciate it. I’ll let you know what happens next weekend if I get some time to work on it. I’ll be ordering some parts $$$&&

 

[70chall440]

One of the biggest mistakes made with RTV and gasket maker is assembling too quickly and tightly; you usually only manage to push out the sealer. The advice above is good, don't tighten it down right away, have to let the RTV solidify some.

Everyone has their own techniques.

 

[70chall440]

When I glue my VC gaskets with RTV I use it sparingly. Once I put the gasket on I lay them flat on the floor overnight. No issues.

Thats fine for the gasket on the cover, however his leak is more than likely coming from the head side and the poor surface there.

 

[khryslerkid]

After getting shut down by the starter on the line for a drip couple times back in the '80s I made a fix that worked. I had a certain set of heads that I had tried numerous gaskets and covers on with no luck. Set up the heads on the Bridgeport and ran in the rail and it had low spots over 1/8" from casting irregularities. Milled the rail and could use any cover or gasket without problems.

I found that checking the head surface isn't that easy without setting it up on a mill as you did. When I first installed my Cal Customs aluminium covers I installed them dry. As I was installing plug wires I noticed light showing through under the gasket on the front corners. That's when I pulled them and did what I posted earlier with the gasket maker. I believe it was more from the head not being flat than the valve covers.

 

[dart4forte]

Thats fine for the gasket on the cover, however his leak is more than likely coming from the head side and the poor surface there.

Agree

 

[70chall440]

Agree

On the head side of the gasket, I would put a bead of RTV or better yet use the Right Stuff, let it set up for a little while and get a little firm, then assemble it. I just put a gasket on a 440 and used the thick Felpro gaskets which I really like, they tend to smash down and fill a lot of depressed areas on the heads.

 

[dart4forte]

I found that checking the head surface isn't that easy without setting it up on a mill as you did. When I first installed my Cal Customs aluminium covers I installed them dry. As I was installing plug wires I noticed light showing through under the gasket on the front corners. That's when I pulled them and did what I posted earlier with the gasket maker. I believe it was more from the head not being flat than the valve covers.

when I do a motor I always ask the shop doing the machine work to check and true if needed the VC surfaces.

 

[dart4forte]

On the head side of the gasket, I would put a bead of RTV or better yet use the Right Stuff, let it set up for a little while and get a little firm, then assemble it. I just put a gasket on a 440 and used the thick Felpro gaskets which I really like, they tend to smash down and fill a lot of depressed areas on the heads.

Agree

 

[Bee1971]

"They’re the aluminum mopar performance ones."

"changed gaskets about 6 times"



Sounds like the gaskets are not the issue , I have never used RTV on any valve cover - Maybe a little contact cement to hold it in place in a few areas

At the very least , start with what RT Boy 67 said

Then maybe different valve covers